This is a service project for the resynthesis of materials not available on the open market or from the original supplier in amounts required by the Cancer Treatment Program. Compounds assigned for preparation are for the completion of definitive testing or for clinical or preclinical evaluation. Assignment of compounds for resynthesis will originate with the Drug Development Branch, NCI, and involve a wide variety of chemical structures. The major portion of the project will be devoted to the preparation of kilogram quantities of material requiring pilot plant facilities. Many of the preparations will involve multi-step sequences. The project may also perform large scale extraction and isolation of natural products needed by the Program.